1. Field Of the Invention
This invention relates to industrial floor scales having load cells or strain gauges connected to a metal frame having a load-bearing platform to weigh industrial materials up to about 5,000 pounds. Until now, such scales have been of unitary structure, and have weighed in excess of three hundred thirty pounds, and could not be carried or moved by a single worker.
2. Description of the Related Art
The following patents relate to platform scales:
______________________________________ Patent Number Inventor Date ______________________________________ 2,499,033 Oberholtzer 1950 3,512,595 Laimins 1970 3,666,032 Maffia, et al 1972 3,933,212 Bradley, et al 1976 4,261,428 Bradley 1981 4,350,218 Soderholm 1982 4,874,050 Strasser, et al 1989 4,949,798 Strasser, et al 1990. ______________________________________
Oberholtzer's weighing platform is bolted to four beams which are bolted to corresponding corner posts which are rigidly attached to a base member. A strain gauge is bonded to each beam to measure strain from impact loads on the platform. Laimins' scale has a load platform comprising hardwood planks which are secured to the underlying framework. Laimins describes a foundation for his scale, so it would not appear to be portable. A second embodiment of Laimins' scale is limited to 500 pound capacity (Col. 7, lines 49 ff.). It is not stated whether this scale is portable.
Maffia, et al describe a bench and portable platform scale in which force applied to the scale platform is transmitted to a transfer lever arm through flexure plates. This patent states that the weighing platform is supported by the four corner posts, but the description does not state whether the weighing platform is attached. In any event, such scales are relatively limited in capacity compared to industrial floor scales. This scale is described as having a 1,500 pound capacity. The material of the platform is not described, but it is believed to be steel, because the frame is steel.
Bradley, et al '212 is primarily concerned with making a very low profile platform scale having a two layer platform which is bolted together. Bradley, et al '428 includes a single load cell and elaborate stabilizing means interconnected between the base platform and the load supporting platform.
Soderholm U.S. Pat. No. 4,350,218 describes a platform scale having four load cells, one in each corner. The platform is connected to the frame.
Strasser, et al U.S. Pat. Nos. 4,874,050 and 4,949,798 describe "portable" deck truck scales which have deck structures reinforced with "V" shaped support ribs. The deck in U.S. Pat. No. 4,874,050 is concrete poured on a metal deck, and the scale is said to be "portable". The deck in U.S. Pat. No. 4,949,798 is similar, but does not include poured concrete. "Portability", as used in these patents, is not believed to mean "movable" by a single worker, but transportable by a front end loader, or other large mechanical device.